ABADDON ("Realm of Destruction"):

In rabbinic and New Testament literature, the second department of Gehenna, the nether world; almost synonymous with Sheol (Midr. Konen; compare Joshua ben Levi in 'Er. 19a). In Rev. ix. 11 Abaddon is personified as the Angel of Hell: "And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon." In the Old Testament, however, the word is peculiar tothe "Wisdom" literature, being found in Job, xxviii. 22, xxvi. 6, xxxi. 12; Prov. xv. 11; Ps. lxxxviii. 12. In Prov. xxvii. 20 the Hebrew text has Abaddoh, but the marginal reading has Abaddon.